What is the expected genotypic ratio in the F2 generation of a dihybrid cross? (
Practice Questions
Q1
What is the expected genotypic ratio in the F2 generation of a dihybrid cross? (2019)
1:2:1
3:1
9:3:3:1
1:1:1:1
Questions & Step-by-Step Solutions
What is the expected genotypic ratio in the F2 generation of a dihybrid cross? (2019)
Step 1: Understand what a dihybrid cross is. It involves two traits, each with two alleles.
Step 2: Identify the parental generation (P generation) with two different traits. For example, let's say we have tall (T) vs. short (t) plants and yellow (Y) vs. green (y) seeds.
Step 3: The F1 generation will be heterozygous for both traits (TtYy) when you cross the P generation.
Step 4: When you cross two F1 individuals (TtYy x TtYy), you create the F2 generation.
Step 5: Use a Punnett square to determine the combinations of alleles in the F2 generation. You will have 16 boxes in total.
Step 6: Count the different genotypes that appear in the F2 generation. You will find 9 different combinations for dominant traits, 3 for one dominant and one recessive, 3 for the other dominant and recessive, and 1 for both recessive traits.
Step 7: Write down the expected genotypic ratio: 9 (dominant for both traits) : 3 (dominant for the first trait, recessive for the second) : 3 (recessive for the first trait, dominant for the second) : 1 (recessive for both traits).
